Friction particle for brake lining

ABSTRACT

A FRICTION PARTICLE, USEFUL IN APPLICATIONS WHERE CASHEW NUT SHELL OIL FROICTION PARTICLES HAVE BEEN U SED, MAY BE PREPARED BY THE REACTION AT A TEMPERATURE FROM ABOUT 225 TO ABOUT 400 DEGREES FAHRENHEIT OF A NON-OXYALKYLATED RESOLE WITH RESIN SELECTED FROM THE GROUP CONSISTING OF AN OXYALKYLATED RESOLE, AN ALKYLATED RESOLE, AN ALKYLATED NOVOLAC, AN OXYALKYLATED NOVOLAC, AND MIXTURES THEREOF UNTIL IT IS INSOLUBLE, INFUSIBLE, AND DOES NOT SOFTEN SLIGHTLY UNDER MECHANICAL FORCE AT TEMPERATURES BELOW ABOUT 400 DEGREES FAHRENHEIT, AND HAS SUBSTANTIALLY NO COHESIVE OR BONDING STRENGTH.

United States Patent 3,658,751 FRICTION PARTICLE FOR BRAKE LINING FrankS. Grazen, Melvin L. Buike, and Frank M. Bryzmsky, North Tonawanda,N.Y., assignors to Hooker Chemical Corporation, Niagara Falls, NY. NoDrawing. Filed Oct. 30, 1969, Ser. No. 872,753 Int. Cl. C08g 37/18,51/10 US. Cl. 260-38 Claims ABSTRACT OF THE DISCLOSURE This inventionrelates to novel cured phenolic resins to be used as a friction particlematerial. It is especially useful where cashew nut shell oil frictionparticles, called Cardolite, have been used in the past.

Phenol aldehyde, or hydroxy aromatic-aldehyde condensation productshaving methylol side or end groups are known in the art as resoles. Theyare formed from condensing a phenol with an excess of aldehyde and withan alkaline catalyst, also known as one-stage resins and are of thethermosetting type. Except when oxyalkylated, they are self-setting.That is, upon the application of heat there results the formation of aresite, which is an infusible three-dimensional polymer.

Novolac phenol aldehyde resins, on the other hand, are phenol-endedchain polymers. They are formed by the reaction of an aldehyde with anexcess of phenol in the presence of an acid catalyst and/ or heat. Theyare thermoplastic, permanently soluble and fusible. However, upon theaddition of a curing agent, they can be cured into an insoluble,infusible resin. Thus, novolac resins are known as two-stage resins.

:Phenol aldehyde condensation products have been used as binders forabrasive materials. However, to our knowledge, the novel cured phenolaldehyde products of this invention have not been used as a frictionparticle per se.

As used herein friction particle is intended to mean having theproperties of substantially no softening at elevated temperatures andwill not flow together or cohere with other particles, as a frictionbinder would, or fuse with like friction particles. It is insoluble,having an acetone extraction of less than 35 percent and often less than5 percent; it is infusible, i.e., has gone beyond the B stage, to the Cstage. It will not melt at 700 degrees Fahrenheit. A friction particleis held in place with a friction binder.

As used herein, a friction binder has the properties of flowability, andhas adhesive and cohesive bonding action and thereby binds together theasbestos and other additives (including a friction particle) necessaryfor building a brake lining or other similar article of manufacture. Thebinder, as supplied to the industry, will melt as a dry powder or is aliquid resin, and can be either an A stage or B stage resin. The binderbecomes a C stage resin after it is combined with the other ingredientsand cured.

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This composition of the binder, friction particle and other additives,is heated to about 300-400 degrees Fahrenheit and pressed at about500-2000 pounds per square inch in order to form a brake liningcomposition, or clutch facing or other braking device. Thus, thefriction particle is substantially insoluble and infusible, softeningonly at elevated temperatures (i.e., above about 400-500 degreesFahrenheit).

It has now been found that a composition of matter useful as a frictionparticle can be prepared by the reaction at a temperature from about 225to about 400 degrees Fahrenheit of a non-oxyalkylated hydroxy aromatichydrocarbon-aldehyde resole with a resin selected from the groupconsisting of an oxyalkylated hydroxy aromatic hydrocarbon-aldehyderesole, an alkylated hydroxy aromatic hydrocarbon-aldehyde resole, analkylated hydroxy aromatic hydrocarbon-aldehyde novolac, an oxyalkylatedhydroxy aromatic hydrocarbon-aldehyde novolac, and mixtures thereof,until it is insoluble, infusible, and does not soften slightly undermechanical force, such as a spatula, at temperatures below about 400degrees Fahrenheit, and has substantially no cohesive or bonding actionor strength. The crude material is initially in lump form, which is thenground to the size specification of the customer. The first said resolecan be alkylated but not oxyalkylated. Among the preferred embodimentsof this invention are the following:

(1) The reaction product of between about 5 and about 40 percent byweight of an oxyalkylated resole with between about 95 and about 60percent by weight of one or more of (a) one or more non-oxyalkylated,non-alkylated resoles,

(b) an alkylated resole,

(c) a mixture of a non-oxyalkylated alkylated resole and anon-oxyalkylated, non-alkylated resole,

(d) a mixture of a non-oxyalkylated, non-alkylated resole and anon-oxyalkylated alkylated novolac, and (e) a mixture of anon-oxyalkylated, non-alkylated novolac and a non-oxyalkylated,non-alkylated resole.

(2) The reaction product of between about 95 and about 60 percent byweight of a non-oxyalkylated, nonalkylated resole with between about 5and about 40 percent by weight of one or more of:

(a) an oxyalkylated novolac, and (b) a non-oxyalkylated, alkylatedresole.

(3) The reaction product of between about 5 and about 40 percent byweight of an oxyalkylated novolac with between about 95 and about 60percent by weight of one or more of:

(a) two or more non-oxyalkylated, non-alkylated resoles,

(b) an alkylated resole.

(c) a mixture of an alkylated resole and a non-oxyalkylated,non-alkylated resole,

(d) a mixture of a non-oxyalkylated, non-alkylated resole and anon-oxyalkylated alkylated novolac, and

(e) a mixture of a non-oxyalkylated, non-alkylated resole and anon-oxyalkylated, non-alkylated novolac.

(4) The reaction product of between about 5 and about 95 percent byweight of a solid, B-stage non-oxyalkylated, alkylated resole, withbetween about 95 and about 5. percent by weight of a liquid, A-stage,non-oxyalkylated, alkylated resole.

(5) The reaction product of between about 70 and about percent by weightof a non-oxyalkylated, alkylated resole, with between about 30 and about10 percent by weight of a non-oxyalkylated, alkylated novolac.

(6) The reaction product of between about 5 and about 50 percent byweight of a non-oxyalkylated, alkylated resole, with between about 5 andabout 30 percent by weight of a non-oxyalkylated, alkylated novolac, andwith between about 25 and about 90 percent by weight of anon-oxyalkylated, non-alkylated resole.

In general, an oxyalkylated aromatic material, whether it is a novolacor a resole, will not react with a novolac by itself. The methylolgroups on a resole are believed to be needed to react with the polyolgroups of the oxyalkylated materials.

The friction particle is formed by blending and reacting the resole withthe novolac, or oxyalkylated resole. Usually, the resole andoxyalkylated resole or oxyalkylated novolac are both liquids, soblending is easily achieved. However, when one is a solid, it ispowdered and mixed with the liquid. When both are solids, both are dryblended such as by ball milling together. Then they are mechanicallyblended, such as by being passed through a hammer mill equipped with aquarter mesh screen.

Following blending, the resins are heated to about 225 degreesFahrenheit to about 400 degrees Farhenheit, and preferably from about325 degrees Fahrenheit to about 375 degrees Fahrenheit, until a resin offriction particle consistency is formed.

Examples of phenols which can be used in preparing a phenol aldehyderesole or novolac for use in practicing the invention include ortho-,paradirecting hydroxy or amino aromatic compounds having 6 to 24 carbonatoms such as phenol itself (C H H), naphthol, anthranol and substitutedderivatives thereof where the substituents on the aromatic compound areindependently selected from H, Cl, Br, F, NH; and

(a) Alkyl groups or radicals of l to 60 carbon atoms, preferably of 1 to30 carbon atoms, and their various isometric forms and substituted onthe aromatic nucleus in the ortho or para position;

(b) Cycloalkyl groups of 5 to 12 carbon atoms such as cyclohexyl,cyclopentyl, methylcyclohexyl, butlycyclohexyl, and so forth;

(c) Alkyl, aryl and cycloalkyl ketonic groups wherein the hydrocarbonportion is as defined above in (a) and (d) Alkyl, aryl and cycloalkylcarboxylic groups wherein the hydrocarbon part is defined as above in(a) and (b);

(e) Aryl groups of 6 to 24 carbon atoms such as phenyl, naphthyl,anthryl, and the like;

(f) Aryl substituted alkyl wherein the aryl is phenyl which may containlower alkyl and/ or hydroxy substituents so that the resulting hydroxyaromatic is, for example, a bisphenol; and

(g) Mixtures of the aforesaid hydroxy aromatics.

' Suitable substituted phenols include the following: para-phenylphenol, para-benzyl phenol, para-beta-naphthyl phenol, cetyl phenol,para-cumyl-phenol, para-tertbutyl phenol, sec-butyl phenol,para-tert-amyl phenol, para-tert-hexyl phenol, para-alpha-naphthylphenol, parahydroxyacetophenone, para-hydroxybenzophenone, paraisooctylphenol, para-tert-octyl phenol, para-cyclohexyl phenol, para-d-limonenephenol, para-l-limonene phenol, a phenol alkylated with oleic acid, suchas phenol alkylated with oleic acid, para-decyl phenol, para-dodecylphenol, para-tert-dccyl phenol, butyl naphthol, amyl anthranol,para-nonyl phenol, para-methyl phenol, bisphenols such aspara,para'-isopropylidene' diphenol, para, para'-methylene diphenol, aswell as the corresponding ortho-derivatives of the previously mentionedcompounds such as ortho-butyl phenol and ortho-nonyl phenol as well asmixtures thereof, and aniline.

Mixtures of various hydroxy aromatic compounds mentioned herein also maybe used.

Included among the phenolic reactants which may be used are those knownas the cresylic acids and these often comprise a heterogeneous mixtureof having two reacting hydrogen positions on each of them; that is,compounds unsubstituted in the orthoand para-positions of the molecule,to compounds that only have one functional position, and hence,realtively unreactlve. These compounds may include the following:3,5-xylenol, mcresol, 3,4-xylenol, 2,5-xylenol, 2,3xylenol, phenol,pcresol, ortho-cresol, 2,4-xylenol, and 2,6-xylenol. Crescylic acids ortar acids are generally applied to phenol and its homologs which mayinclude cresols, xylenols, trimethyl phenols, ethyl phenols, and higherboiling materials such as dihydroxy phenols, polycyclic phenols and thelike. They are often obtained by a low-temperature trimerization ofcoal, lignite, and the like, or a conventional hightemperature coke oventar, or the liquid product of petroleum cracking both thermo andcatalytic, shell oil, coal hydric hydrogenation products, and the like.

Polyhydroxy aromatic reactants, such as resorcinol, may also be used.

Particularly useful in this invention are mixtures of aniline and phenolto react with an aldehyde or ketone to produce either a novolac or aresole, depending on the other conditions described above.

Also useful in the invention are mixtures of urea and phenol to reactwith the aldehyde or ketone to produce either a novolac or a resoledepending on the other conditions described above.

Among the aldehydes which may be used within the scope of this inventionto produce either the resole or the novolac, are formaldehyde or any ofits variations, such as 37 percent formalin concentration orpara-aldehyde, acetaldehyde, propionaldehyde, isobutylaldehyde,isopentaldehyde, and the like. The aldehyde should have not more than 8carbon atoms and should not detrimentally affect the resinification oroxyalkylation of the resin. Preferred aldehydes are those having from 1to 4 carbon atoms, such as formaldehyde, which may be in aqueoussolution (37 percent), or in any of its low polymeric forms such asparaform or trioxane. Other aldehydes include paraaldehydes, furfural,Z-ethyl-hexanal, ethylbutyraldehyde, heptaldyde and glyoxal,benzaldehyde and crotonaldehyde.

Novolacs To prepare a novolac, the proportion of aldehyde to becondensed with the hydroxy aromatic compound may be varied in order toobtain different molecular weights, and the viscosity of the finishedresin may be controlled by the mole weight of the novolac; preferablythe proportion of aldehyde employed is from 0.5 to 1.0 per mole of thehydroxy aromatic compound.

Among the substituted phenols which may be used to prepare the novolacsfor this invention are those substituted with long-chain ethylenicallyunsaturated hydrocarbons, such as the linseed-type oils. However, it itwithin the scope of this invention to employ any animal and/ orvegetable oil which achieves the objects of this invention based on thesimilarity in properties with the longchain hydrocarbon oils. Such oilswould be positioned on the phenol in the orthoor parapositions, andpreferably in the paraposition. Many of them are similar in propertiesto linseed oil having non-conjugated unsaturation of at least 50 iodinenumber, and have sufficient compatibility with the novolac after it ispolymerized. Safilower oil is typical of these oils. It may be in theform of a glycerol ester of the fatty acids wherein the fatty acids areof a composition comprising more than 40 percent by weight of linolenicacid. The remaining percentages of fatty acid can be any saturated orethylenically unsaturated fatty acid having 12 to 22 carbon atoms andmore preferably oleic and linolenic acid so that the fatty esters havean iodine number of at least 50. The iodine value (iodine number) is ameasure of unsaturation, and is defined as the number of grams of iodinerequired per grams of unsaturated material to obtain the saturatedmaterial. In addition to the preferred glycerol ester, other polyhydricalcohols can be reacted with the described fatty acids to produce a lowacid number ester of a polyol having 2 or more hydroxyl groups. Typicalpolyols include ethylene glycol, diethylene glycol, pentaerythritol,dipentaerythritol, sorbitol and the other polyhydric alcohols.

The acid catalyst to be used when preparing the novolacs to be used inthis invention may be chosen from oxalic acid, sulfuric acid,hydrochloric acid and other strong acids used in the art for preparingnovolacs. In addition, wetting agents of the anionic type, such as sodium alkylaryl sulfonates, are also useful as secondary catalysts inpreparing novolacs.

The two-stage resins are curable by reaction with hexamethylenetetramine to form dibenzyl and tribenzyl amines, as well ashexatriphenol. One may also use ammonium hydroxide, which reacts withthe formaldehyde to form hexamethylene tetramine. Other amines may alsobe used, such as ethylene diamine or ethylene triamine, or methylamines,etc. These can be used to react with formaldehyde to form a compositionsimilar to hexamethylene tetramine. The resulting compound would be analdehyde donor.

The phenol aldehyde novolac type resin is prepared by charging thedesired phenol and aldehyde raw materials and catalysts to a reactionvessel. The reaction begins at about 100 degrees centigrade and proceedsunder temperatures up to about 200 degrees centigrade, at any pressureup to about 100 lbs/square inch gauge for about one and one-half hours,or until the desired degree of polymerization has taken place.Thereafter, the catalyst is neutralized where necessary, and the excessreactant, water, and other materials are taken off by dehydration andthe molten resin is discharged from the vessel. It has been found that anovolac which has not been neutralized and is stable will cure morerapidly with a resole than a novolac which has been neutralized.

From the foregoing, it is apparent that many hydroxy aromatic compoundsmay be used in practicing the present invention to provide a novolacwhich can be then reacted With an hydroxy aromatic aldehyde resole toform the friction particle of this invention, provided the aromatichydroxyl group is reactive and the hydroxy aromatic compound is capableof reacting with an aldehyde or a mixture of aldehydes to produce anovolac condensate. Pure, refined phenols may be used, but this is notnecessary. For instance, phenols may be alkylated and then may bereacted in crude form with an aldehyde. In such crude form, the phenolsmay contain some polyalkylated, as well as non-alkylated, phenols.

The process for alkylation of a phenol is well-known in the art. First,dehydration (of water) is carried out with vacuum at elevatedtemperatures, for instance, between about 100 and about 150 degreescentigrade under a vacuum of between about 20 and about 30 inches ofmercury. Then, the dehydrated phenolic material is acidified to a pH ofbetween about 1 and about with- H SO or in some cases BF Following this,a terpene or vegetable oil is added and a reaction mixture heated tobetween about 80 and about 140 degrees centigrade at atmosphericpressure. The molar ratio of reactants is between about 0.1 mole ofterpene or vegetable oil per mole of phenol to about 2.5 mole of terpeneor vegetable oil per mole of phenol. When tung oil is employed as avegetable oil in the alkylation, use of ER, to acidity would causegelation, so it is not used, but H 80 can be used.

The proportion of aldehyde to be condensed with the hydroxy aromaticcompound to form a precondensate may be varied to prepare novolacs ofdifferent molecular weights. Viscosity of the finished precondensate maybe controlled by the mole weight of the novolac. Preferably, theproportion of aldehyde employed varies from about 0.5 to 1.0 mole permole of phenol when a monoor difunctional phenol is used. In instanceswhere a trifunctional phenol is used, i.e., unsubstituted in theorthoand para-positions, a preferred upper limit of the aldehyde may beabout 0.70 mole of aldehyde per mole of phenol so as to minimize theformation of insoluble, infusible condensates. It is preferred that thealdehyde and phenol be condensed using an acid catalyst to shorten thetime required for complete condensation of the reactants. Suitable acidcatalysts include sulfuric acid, hydrochloric acid, and oxalic acid.These catalysts are generally employed in the amount of 0.1 to about 5percent by weight of phenol to be condensed.

Where a mixed aldehyde, phenol-aldehyde precondensate is to be prepared,it is formulated by charging .the desired phenol and aldehyde rawmaterials and catalysts to a reaction vessel. The reaction proceedsunder temperatures from about 25 to about 150 degrees centigrade at apressure from about ambient up to about 100 pounds per square inch gaugepressure for a period of time from about 5 minutes to about 5 hours, asuitable time being about one and one-half hours, or until the desireddegree of condensation has taken place. The phenol is first reacted withthe longer-chain aldehyde to form a phenollonger chain aldehydeprecondensate, followed by a second-step reaction of the phenol-longerchain aldehyde precondensate with formaldehyde to form a thermosettablephenol aldehyde precondensate material. In the second step, thereactants are refluxed at atmospheric pressure, although higher refluxtemperatures up to about 150 degrees centigrade can be used by employingelevated pressure. The formaldehyde can be added all at once in thesecond step, or added gradually. If the formaldehyde is added all atonce, then a temperature range between about 50 and about 60 degreescentigrade is used at the beginning of the second-step reaction, untilthe exothermic reaction subsides, and then the temperature is increasedslowly to between about 70 and about degrees centigrade and held untilfurther exothermic reaction subsides, and then the reaction mixture isheated to reflux temperature which is about degrees centigrade atatmospheric pressure. If elevated pressure is used, then the refluxtemperature can be increased to as high as about degrees centigrade. Ifthe formaldehyde is added gradually in the second step, then atemperature range between about 95 and about 140 degrees centigrade canbe used. The catalyst is then neutralized and the excess reactant, waterand other materials are taken off.

While the precondensate is still at an elevated temperature, from about25 degrees to about degrees centigrade, but below the boiling point ofthe resultant solution or suspension, with about 100 degrees centigradebeing very suitable, it may be reduced in viscosity by addition ofsuitable solvent. The amount of solvent may vary from about 10 to 70percent of the precondensate by weight and a suitable ratio ofprecondensate to solvent is about 10 parts of precondensate to 9 partsof solvent. The controlling factor is the resulting viscosity of theprecondensate prepared, rather than the actual volume of solventcharged. Among the solvents which may be used for this purpose areethanol, methanol, toluene, xylene, ketones, such as acetone, andmethylethyl ketone, and mixtures of aromatic and aliphatic hydrocarbons,such as mixtures of benzene and mineral spirits, or benzene and acetone.

Oxyalkylation Oxyalkylated resins are prepared which preferably containsubstantially no free reactive hydroxy aromatic groups, for example,less than about 0.5 percent of the aromatic hydroxy present originallyin the hydroxy aromatic or hydroxy aromatic aldehyde condensate. Toremove the aromatic hydroxys, the hydroxy aromatic aldehyde resin can bereacted with a compound which etherifies the aromatic hydroxyl groups sothat almost all of the aromatic hydroxy groups present in each hydroxyaromatic aldehyde condensate unit are so reacted.

The preferred method of hydroxyalkylation is by reaction with compoundscontaining a mono-oxirane ring. Such compounds include ethylene oxide,propylene oxide, butylene oxide, styrene oxide and cyclohexene oxide,glycidol and epichlorohydrin. Many other monoepoxides can be used, butthe alkylene oxides containing not more than 6 carbons are generallypreferred. Additional useful compounds are phenyl glycidyl ether andrelated compounds prepared from the reaction of epichlorohydrin andmonofunctional alkylated and halogenated phenols such aspentachlorophenyl glycidyl ether.

Catalysts for the reaction of the oxirane ring compounds and phenolichydroxy groups may be alkali or alkaline earth hydroxides, primaryamines, secondary amines, tertiary amines or basic alkali salts. Theseinclude sodium, potassium, lithium, calcium and barium hydroxides,amines such as methyl, dimethyl, diethyl, trimethyl, triethyl,tripropyl, dimethyl benzyl, dimethyl hydroxyethyl,dimethyl-Z-hydroxypropyl and the like, and salts of strong bases andweak acids such as sodium acetate and benzoate.

The reaction may be carried out at temperatures of about roomtemperature of 250 degrees centigrade, and preferably in the absence ofsolvents, although solvents may be used to reduce viscosity whendesired. When oxyalkylating resoles, the reaction should be carried outat lower temperatures than when oxyalkylating novolacs, because there isa possibility that reaction of the methylol group with other methylolgroups gives methylene linkages, formaldehyde and gelation. Whenoxyalkylating a novolac, temperatures between room temperature and about200 degrees centigrade can be used. When oxyalkylating a resole,temperatures between room temperature and about 100 degrees centigrademay be used.

The aromatic hydroxy of the novolacs may also be hydroxyalkylated byreacting alkylene halohydrins with the aromatic hydroxy] usingequivalent amounts of an alkali metal hydroxide to bring about thereaction. Suitable alkylene halohydrins are ethylene chloroandbromohydrins, propylene chloroand bromohydrins, 2,3-butylene chloroandbromohydrins, and glyceryl chloroand bromohydrins.

Another method for hydroxyalkylating novolacs is reaction with alkylenecarbonates such as ethylene carbonate and propylene carbonate, using acatalyst such as potassium carbonate.

At least one mole of alkylene oxide or other etherifying or esterifyingagent is required per mole of aromatic hydroxyl. However, resinsprepared by reaction with up to 7 moles of alkylene oxides per mole ofphenolic hydroxyl have been found to be useful.

Resoles The liquid one-stage resin (resole) which forms a part of thisinvention may be formed by reacting an hydroxy aromatic compound with anexcess of formaldehyde in alkali such as sodium hydroxide dissolved inwater. The reaction mixture is gradually heated to reflux and held atreflux until less than about 1 percent of free formaldehyde remains.This provides a preferred reaction product which has less than 2 percentof the formaldehyde unreacted, although this is not critical in thisprocess. Less than 2 percent free CH O is desirable. The reactionmixture is then cooled and the catalyst neutralized with some acid suchas glacial acetic acid and the pH is adjusted to roughly 6 to 7.5. Thereaction mixture may be then further reacted with hexamethylenetetramine or some other aldehyde donor, i.e., curing agent. The resin isthen dehydrated to between about 50 to 95 percent solids, and preferablybetween about 81 and 85 percent solids.

The alkyline catalyst used in preparing the resoles to be used in thisinvention may be any of those known in the art; for instance, sodiumhydroxide and calcium hydroxide. In general, the alkali metal hydroxidesand the alkaline earth metal hydroxides and ammonium hydroxide and theamines such as triethanol amines may be used.

Following the intercondensation reaction to form a resole, astoichiomet-ric quantity of a strong acid such as sulfuric acid,hydrochloric acid, phosphoric acid or oxalic acid, or the like, is addedto the reaction mixture in order to neutralize the alkaline condensationcatalyst. Sulfuric acid is conveniently employed to neutralize a sodiumhydroxide catalyst. The alkaline catalyst may also be neutralized bydilution through repeated washing, however, it is preferred to use anacid. The final resin should have a pH between about 5.5 and 7.5 forgood stability.

The hydroxy aromatic compound employed in a resole can be alkylated, ifdesired, with alkyl groups containing 1 to 12 carbon atoms, or withunsaturated groups, including the long-chain unsaturated vegetable oranimal oils, to form alkylated hydroxy aromatic compounds that whenreacted with an aldehyde form heat reactive resoles. These includealkylene groups of 2 to 36 carbon atoms, fatty acids, polyethers, alkylethers, polyesters and polyols and mixtures of these.

Among the high molecular weight or polymeric materials containingaliphatic carbon-to-carbon unsaturation, there are included suchnaturally occurring materials as unsaturated vegetable, fish or animaloils such as linseed, soya, tung, sesame, sunflower, cotton seed,herring, menhaden, and sardine oils, etc., or chemically modifiednaturally occurring materials such as allyl ethers of starch, celluloseor acrylate esters thereof, etc., synthetic drying oils, polymersobtained by polyetherification of such unsaturated compounds such asmaleic, fumaric, itaconic, aconitic, chloromaleic, dimerized fattyacids, anhydrides or acids from allyl glycerol, methallyl glycerolethe'r, glycerol monoacrylate, butene diol, pentene diol, or polymersobtained by polyetherifica'tion of the unsaturated polyols. Other oilsinclude castor oil, tall oil, oiticica oil, safllower oil, and the like,oleic and linolenic acids. These fatty acids have from 12 to 22 carbonatoms. They are often in combination as a glycerol ester or incombination with other polyhyd-ric alcohols or polyols such as ethyleneglycol, diethylene glycol, pentaerythritol, dipentaaerythritol,sorbitol, and the like polyhydric alcohols.

The blending and reacting of the resole with the other components inaccordance with this invention may be in various proportions, dependingupon the ultimate properties desired in the friction particle to -beproduced, but will generally be in the range of about 60 to about weightpercent of the non-oxyalkylated resole based on the total weight ofresin components.

It is to be understood that the oxyalkylated resole or oxyalkylatednovolac described herein will not be a friction particle alone unlessreacted with a non-oxyalkylated, nonalkylated resole resin or with anonoxyalkylated, alkylated resole resin. The oxyalkylated resoleproductis a liquid and will not cure. The preferred compositions of theinvention contain at least one of an oxyalkylated resole and anoxyalkylated novolac in combination with the nonoxyalkylated resole'.

The friction particle of this invention may be used alone or with otherfriction materials known in the art. A typical friction element containsabout 30 to 60 weight percent asbestos fiber, up to 40 weight percentother inorganic filler and abrasives, about 5 to 15 weight percentorganic filler, including the particle of this invention, and about 15to 30 weigh-t percent binder; all percents are by weight 1 of totalcomposition. Asbestos fiber, other abrasive materials and fillermaterials are charged into a mixer followed by the addition of a binder,such as a varnish ma-- terial. The materials are kneaded until thefiber, abrasives, and any fillers are thoroughly wetted and a uniformmass is obtained. The mass is discharged from the mixer, rolled out intosheets or extruded or pressure molded and dried, after which it is readyfor further processing into friction elements.

The abrasives, that is, the friction imparting agents and fillers, whichmay be used in addition to the abrasive material disclosed and claimedherein, within the scope of this invention include, but are not limitedto brass chip's, metal shavings and fillings, silica, talc, wood flour,chalk, clay, mica, fiber glass, felt, carbon black, graphite, metalnitrides and oxides, and ground cashew nut shell oil polymerizate. Theseabrasives and fillers may be used in addition to the friction particleof this invention to achieve the particular amount of bulk andcoefiicient of friction desired. Some consumer specifications specifythat the friction particle should be 90 percent finer than 20 mesh andcoarser than 100 mesh. 'Other consumer specifications call for coarseror finer friction particles.

The following examples are given to further illustrate the invention.Unless otherwise indicated, all parts are by weight and temperatures indegrees centigrade.

EXAMPLE 1 Part A (The resole) A reaction vessel is charged with 100parts of phenol, parts of cresylic acid, 110 parts of formalin (37percent formaldehyde) and 1.0 part of flake caustic dissolved in 4 partsof water. This reaction mixture is heated gradually to reflux and heldat reflux to less than 5 percent free formaldehyde and cooled to 70degrees centigrade, after which 1.5 parts of glacial acetic acid isadded which neutralizes this composition to a pH of 6.8-7.2. After thepH range is achieved the resin is dehydrated to 81-85 percent solids andcooled to room temperature. The resultant product is a viscous liquid,and is identified as resin Ra in Table V.

Part B (The oxyalkylated novolac) The oxyalkylated novolac may also bereferred to as a polyol of a novolac which is oxyethylated, using fromabout one mole to about 7 moles of ethylene oxide to 1 mole of phenol,depending on the properties desired. For this example, a resin was usedwith a ratio of 2 moles of ethylene oxide to one mole of phenol.

A typical modified phenol-aldehyde condensation product is prepared byintroducing 3,000 parts phenol, 13 parts of oxalic acid catalyst and 6parts of a wetting agent of Nacconol (sodium alkylaryl sulfonate) into ajacketed reactor and heating to 100 degrees centigrade. (The anionicwetting agents of alkylaryl sulfonate type are preferred.) Then 1,110parts of a 37 percent aqueous formaldehyde solution are added to thereactor at a rate that the heat of reaction provides a vigorous reflux.Refluxing is continued for 2 hours after the completion of the formalinaddition. The reactor contents are dehydrated at 180 degrees centigradeand then dephenolated at 200 degrees centigrade at 50 millimetersvacuum. Approximately 2,030 parts of phenol-aldehyde condensate areproduced. Then 7.2 parts of sodium hydroxide are introduced to thereactor. Ethylene oxide is then added to the reactor as either a vaporor a liquid. The reactor temperature is maintained at 190 degreescentigrade for the initial 2 hours and is then permitted to increase tothe range of 200 to 220 degrees centigrade until the addition of 878parts of ethylene oxide is complete. The resulting condensation producthad a hydroxyl number of 370, and a Gardner viscosity at 50 degreescentigrade of about 2,000 seconds, and is resin Nf in Table VI.

The novel friction particle is made by blending 60 parts of Part A with40 parts of Part B, curing 8-16 hours at 325 to 375 degrees Fahrenheit,grinding to the desired screen size necessary for a friction particleuseful in the arts. In this particular example, the blend was cured for16 hours at 350 degrees Fahrenheit and ground to 20 mesh. The resultingparticle was made up into a brake lining, tested by standard proceduresand found to be satisfactory for this use.

EXAMPLE 2 70 parts of Part A and 30 parts of Part B of Example 1 wereblended and reacted, using the same curing cycle as in Example 1. Theresulting product was ground to 20 mesh and found to be superior to apolymerized cashew 10 nut shell oil friction particle known as Cardolitein trade, having softening properties at 500 degrees Fahrenheit whencompressed slightly with an 8 inch spatula wide by 4" long x thickblade). Also the heat loss at 700 degrees Fahrenheit was lower than thatof Cardolite.

EXAMPLE 3 parts of Part A and 20 parts of Part B of Example 1 wereblended and reacted, using the same curing cycle as in Example 1. Theresulting product was ground to 20 mesh and had properties similar tothose of the product of Example 2.

The particles obtained in the above Examples 1, 2 and 3 were superior tofriction particles made from polymerized cashew nut shell oil commonlycalled Cardolite, presently used as friction particles in the brakelining industry. The particles made in accordance with the invention areless subject to migration of components which results in brake liningswith better fade characteristics. The particles of the invention aremore heat resistant and can be made with more uniform quality, withbetter control of end properties. The particles are less toxic to theskin than Cardolite, which has the further disadvantage of being solelyavailable from foreign sources. The prodnets of the invention can alsobe made at lower cost.

EXAMPLE 4 The friction particle (7 parts) of Example 1 was used informulating a mixture comprising 62.37 parts of dry mix, 0.63 part ofhexamethylenetetramine, 16.4 parts of varnish, 20 parts of rubbersolvent (mainly mineral spirits) and 06 part water. The dry mix iscomposed of 93 parts by weight of asbestos shorts, Quebec StandardAsbestos Grade 7K, and 7 parts by weight of the friction particles. Themoisture content of the dry mix is held low between 0.75 and 1.0 percentto avoid any possibility of blistering of the element during cure.

To an internal mixer equipped with a Sigma-type blade were charged thedry mix and hexamethylenetetramine. The dry materials were mixed andblended for 5 minutes. Then the varnish and toluene were added and mixedfor 1 hour until the mass was uniform. The dough-like mix was thendischarged from the mixer and charged to an extruder. The extruder isequipped with a 2 inch by inch rectangular die and has an applied rampressure of to 300 pounds per square inch. The dough-like mix was thenextruded in a shape which 'was satisfactory for brake linings. Theextruded linings were oven dried for 3 hours and with a gradual increaseof temperature up to about 88 degrees centigrade to remove solvents andother volatiles. The linings were then cut to proper length, reheatedfor 2 to 3 minutes at about 163 degrees centigrade, bent or arched tothe desired curvature and placed into forms (i.e., molds) for curing.These linings were then cured for 8 hours at about 205 degreescentigrade. The cured linings after cooling were expanded to the propersize for mounting into brake shoes. The resulting friction elements werefound to be satisfactory for use on automobile brakes.

EXAMPLES 5-12 In Table I, Examples 5-12 are shown in tabular form. Ineach of these examples, (except Examples 10, 11 and 12) the resins wereweighed into a beaker and mechanically mixed. The mix was spread intoaluminum pans (2 /2 inches by 7 inches) and cured in an air-circulatingoven at the specified temperature and time. The formulations for theresoles and novolacs used are given in Tables V and VI, respectively.Example 10 is a repeat of Example 2. In Example 11, a CardoliteNC-104-20 sample of cashew nut shell oil friction particles is given forcomparison purposes. In Example 12, since both resins are liquids, thematerials were mixed in a 15 gallon kettle. In all other respects,however, the procedures and equip ment were the same as the otherexamples in Table I.

TABLE I Resole Novolac Weight ratio Cure Cure Volatile Acetone ExampleResin Resin Resole/ temp., time, loss. extractable number Weight formulaWeight formula novolac 0. hrs percent percent Hot plate behavior at 500F.Spatula test 195 Re 15 Na 90/10 175 16 11.9 2.07 Smoky, softensslightly under spatula pressure. 195 Re 15 Na 90/10 175 16 14.3 3.14 D-225 Rt Na 90/10 175 16 22.7 13. 66 Very smoky, softens sllghtly colotchange. 162 Re 45 Nd 70/30 175 16 13.6 25.61 Smoky, changes to a wet,oily mass, soft. 225 Rt 15 Nd 90/10 175 16 17.9 11.52 Smoky, softensslightly. 140 Re 60 Ni 70/30 0 24.9 21.65 Smoky, very slight soiteningcolor change. Cardolite NC-104-20 Cashew Nut Shell Oil FriotlonParticles 25. 9 2. 59 veiryl strnogyi soitens slightly, oily odor, partca re own. 140 Rg 60 Ni 70/30 120 22 17.27 3.63 Smoky, slight softening,color change.

2.4 grams of hexamethylene tetramine were also added into the mix.

Nora-Weights are in grams; volatile loss is at 700 F. for one hour;acetone extractable test is ASTM D-404-46; all materials tested wereground throng, mesh; ratio is of resin solid content.

The results presented in Table I indicate that the commercial Cardolitefriction particle has a high volatile loss when heated at 700 degreesFahrenheit for one hour, a

The procedure used is set forth in the footnote of Table II. Theformulations for the resoles and novolacs used are given in Tables V andVI, respectively.

TABLE II Ratio Volatile Acetone Example Resole \lovolae resole/ loss,extractable, Hot plate behavior at 500 F.Spatula number formulationformulation novolac percent percent st 15. Rg 7. 51 0. 0 No smoking orsoftening. 16 Ba 6. 29 0. 0 Do. 17 R Ni. 70/30 36. 72 2. 29 Slightsoftening, light smoking. 18 Re and Bi... Nf 70/30 25. 92 3. 70 Slightsoftening, no smoking. 19.. R2 Ne 70/30 8. 17 0. 03 No smoking orsoftening.

0 Ba N 70/30 10. .3 1. 68 Slight sottening.

Bg. Nh 80/20 7. 23 0. 0 Do. Ra Nh 80/20 7.00 0.18 Do. Ru Ne"... 70/30 6.60 0.67 Slight smoking, no softening.

c Hycar 1561latex 90/10 9. 0. 49 Very smoky, melts and turns rubbery. band Rc Ni 70/30 18. 35 0. 58 No smoking, no softening. g Nc 80/20 7. 04. 34 Slight smoking, slight softening. Ra. N P 70/30 6. 0. Slightsmoking, no softening.

NOTE.A]1 components were weighed into a beaker (200 grams total mix) andmechanically mixed. The mix was spread into aluminum pans (2% x 7 andcured in an air circulation oven at 175 C. for 16 hours. Acetoneextractable test is ASTM D-494-46; volatile loss is at 700 F. for onehour; All materials tested were ground through 29 mesh.

low acetone extractable content and deteriorated when heated to 500degrcss Fahrenheit on a hot plate. By contrast, the products of theinvention were more stable at elevated temperatures. The results alsoexhibit the control over properties that is possible with compositionsof the invention. Thus, a low acetone extractable content indicates ahard material, a high acetone extractable content indicates a softermaterial.

EXAMPLES 15-27 EXAMPLES 28-46 particles of variable properties, therebypermitting more 50 flexibility in the supply of friction particleproducts to the In Table H, Examples 15-27 are shown in tabular form.industry.

TABLE III Variations on examples 12 and 14 in Table I Resolo NovolacVolatile Acetone Example iormuformn- Cure Cure loss, extractable, numberlation lation Ratio time temp. percent percent Comments N I /30 1 hr.200 C. 9.4 23. 58 Mixlectl under ggcuum while heating from C. to 105 0.Hot

p a e euresec. 20 Ra Ni 70/30 16 hrs. 120 C. 21.4 28.49 ltllixleat'lunder vgliium while heating from 85 C. to 105 0.,Hot

e curesec. 30 Ra N1 60/40 16 hrs. 120 C. 16.96 41.8 lvliirled underwhile heating from 85 C. to C. Hot

p a e cure sec. 31 Ra Ni 70/30 16 hrs. 120 C. 14.0 24.5 under 2%???while heating from 85 C. to 0. Hot

a e cure sec. 32 Ra Nf 70/30 2 hrs. 200 C. 14. 2 32. 63 R sinsphysically mixed. 3. a a: are a: are asIIIIIIIII n 11 5 g: 1 2 Ia nact-1%. g Resilgs physically mixed.

a o. 37 Rn. Ni 70/30 5 min. 600 23.6 19. 45 Do. 38 Ra Ni 70/30 6 min.600 F 24.8 17. 76 Do. 30 Ra Nf 70/30 7 min. 600 F 25. l 17.47 D0. Ra Ni70/30 8min. 600 F 24.4 15.62 D0. 41 Ra Ni 70/30 10 min. 600 F 24.0 15.09Do. 42 Rg Ni 70/30 3min. 600 F 22.5 5.45 Do. 4 Rg Ni 70/30 2min. 600 F23.3 10.34 Do. 44 Rg Ni 70/30 4 min. 600 F 22.0 7. 61 Do. 45 Rg Nf 70/305111111- 600 F 21.6 7. 02 Do. 46 Rg Nf 70/30 8 min. 600 F 21. 9 4. 81Do.

.No'rE Expeii1nents 28-35 were tested for volatile loss at 600 F. for 2hours and acetone extractable for 16 hours (AS'lM D-40446); Experiments36-46 were tested for volatile loss at 700 F. for 1 hour and acetoneextractable for 4 hours (ASTM D-l04-46).

EXAMPLES 47-452 In Table IV, Examples 47-62 are shown in tabular form.They are presented to further illustrate the variation in resoles andnovolacs which can be employed to l 4 alkylated hydroxyaromatic-aldehyde resole containing substantially no etheri'fiedaromatic hydroxyl groups with a resin selected from the group consistingof at least one of an oxyalkylated hydroxy aromatichydrocarbon-aldeproduce a friction particle. The procedure used was the2 2 11 gz f g g gfig ig ifi iiigf'gi: same as that in Examples 5-9 ofTable I. y y y y 1 y TABLE IV Oxyalky- Percent Percent Example Resole Novolao lated resin volatile Acetone Number formulation formulationformulation Ratio loss extractable Hot plate behavior at 500F.

70/30 21. 19 15. 83 Slight smoke, very slight softening. 70/30 31. 71 0.11 Smoky, softens, odor, oily appearance, slight caking. /35/30 26. 2831. 47 Smoky, slight softening. odor. 35/35/30 22. 77 24. 05 Slightsmoke, slight softening slight odor.

14. 43 15. 24 Smoky, softens, odor, oily, cakes. 11. 57 0. 89 Veryslight smoke, very slight softening. 10. 51 D. 97 No smoke, very slightsoftening. 20. 13 32. 99 Smoky, slight softening, odor, oily. 16. 51 6.59 Slight smoke, slight softening. 17. 88 13. Slight smoke, very slightsoftening. 13. 67 7. 30 Slight smoke, softens, very oily, cakes. 12. 260. 32 No smoke, slight softening. 10. 92 15. 96 Slight smoke, softens,slightly oily, slight coking. Rf Nd 12 56 18. 58 Slight smoke, slightsoftening, slightly oily. R1 and Rg Nd 20/70/10 9. 18 7. 01 Smoky,softens, oily, slight caking. 62 Cardolite N 0-104-20 Cashew Nut ShellOil friction particles Smoky, very slight softening, slight odor.

TABLE V Resin Raw material a b c d e f g h 1 j Afietic acid 0. 18 0. 04Alcohol 28. 90 Ammoniacal liquor. 0. 78 2. 43 Aniline. 4. 86 Casein 1.66 Caustic soda 0. 15 0. 38 0. 36 0. 17 2. 14 Citric acid 0. 18Deodorant 0. 01 Formaldehyde (37.2%) 47. 36 54. 41 49. 44 50. 74 48. 4429. 00 56. 91 45.09 24. 45 180 Hexamethylene tetramine 1. Lime 0. 71 0.81 Melamine (buffered) 12. 31 Meta-Para cresol 1. 78 r MethanoL- 1.Ortho cresnl 3. 85 Oxalic acid-.. 0. 24 0. 02 Para-tertiary butyl phenol21. 60 Para-tertiary octyl phenol 19. 93 Phenol 43. 22 38. 86 32. 93 36.95 18. 77 19. 93 40. 65 52. 37 100. 0 Phosphoric acid 0. 61 Propylenemirle 121. 5 Sulfuric acid- 2. 76 Triethylamine. 7. 2 Urea (shotted) 7.72 Urea formaldehyde- 23. 84 Water 1. 51 1.16 15.57 0.63 1.63 0 48 27.77Xylene 21.

In Resole Hi, the phenol, formaldehyde and 2.5 parts of triethanolaminewere first reacted. This product is then oxypropylated with theremaining specified ingredients.

TABLE VI Novoluc Rosin Formulmtions Resin Raw material a b c d eFormaldehyde (37.2%) Furf ur Isohutyraldehydc Lime- Limonene 19. 19Linseed oil 24. 26 Maleic anhydride. Sodium alkylaryl sulfonate 0. 01

p-Octyl nhonnl Oxalic acid 0. 17 0. 03 Stearlc acid.

Sulphuric acid.

We claim:

1. A friction particle consisting essentially of the product of thereaction at about 225 to about 400 degrees Fahrenheit for about 8 toabout 16 hours of a non-oxycarbon-aldehyde novolac, an oxyalkylatedhydroxy aromatic hydrocarbon-aldehyde novolac, until the resultingproduct is insoluble, infusible and does not soften slightly undermechanical force at a temperature below 400 degrees Fahrenheit, and hassubstantially no cohesive or bonding strength, wherein saidnonoxyalkylated resole comprises about 60 to about 95 weight percent ofthe weight of the resin components.

2. The friction particle of claim 1 which consists essentially of about5 to about 40 percent by weight of an oxyalkylated novolac and about 95to about 60 percent by weight of more than one non-oxyalkylated,nonalkylate resole having substantially no etherified aromatic hydroxylgroups.

3. A brake lining comprising the cured product of the friction particleof claim 1, a resin binder, and an inorganic filler.

4. A brake lining comprising the cured product of about 30 to 60 weightpercent asbestos fiber, up to 40 weight percent other inorganicfillers'and abrasives, about 5 to 15 weight percent of the particle ofclaim 1, and about 1-5 to 30 weight percent binder.

5. A brake lining comprising the cured product of about 30 to 60 weightpercent asbestos fiber, up to 40 weight percent other inorganic fillersand abrasives, about 5 to 15 weight percent of the particle of claim 2,and about 15 to 30 weight percent binder.

References Cited UNITED STATES PATENTS 2,625,530 1/1953 Doelling 61; al.260-838 2,626,942 1/1953 DeGIOOte 260838 10 2,894,931 7/1959 Somenville61111."--- 260-838 2,971,936 2/1961 Dubien et a1 260--838 3,177,0904/1965 Bayes et a1. 260-838 3,455,868 7/1969 DAlessandro 260838 15 JOHNc. BLEUTGE, Primary Examiner us. c1. X.R,

260-19 R, 19 A, 39 R, 39 M, 395 B, 51.5, 838, s40,

20 Dig. 39

@2 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,658,751 Dated April 5, 97

Inventor(s) Frank S. Grazen, Melvin L. Buike and Frank M. Br\ /7in k LIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

r Column 2, line 35, delete "an" and insert ---a non-oxyalkylated,---

Column 3, l ine 7, after "oxyalkylated", insert ---hydroxy--; line 36,delete "isometric" and insert ---isomeric---; line 39, delete "butlycyclo-" and insert ---butylcyclo---. Column line i, delete"realtively" and insert --relatively---; line 5 T, delete "it" secondoccurence, and insert ---is---. Column 7, line 23, delete "of'' andinsert ---to---; line 35, delete "hydroxy" and insert ---hydroxyl line69, delete "and" and insert ---to---; line 70, delete "alkylene" andinsert --.-alkal ine---. Column 8, line 39, delete "dipentaaerythritoland insert ---dipentaerythritol---. Column 9, line 2, delete "fi llings" and insert ---fi l ings---, Column 10, line 1, after "in" insert---the---. Table II, Example 17, delete "light" and insert ---slight--;Table II in the Note last line delete "29" and insert ---20---. TableIII, Example 29, delete "28. 49" and insert ---28.59 Table V for Rawmaterial Urea -formaldehyde the value "23.8 l" should be under column"e" instead of column "d";- Table V heading, delete "Resin" and insert--Resole Resin Formulations Claim 1 cancel entire claim and insert thefol lowing claim in its place:

l A friction particle consisting essential ly of the product of thereaction at about 225 to about +00 degrees Fahrenheit for about 8 toabout 16 hours of about 95 to about 60 percent by weight of a non-oxyalkylated, non-a lkylated resole containing substantial ly no etherifiedaromatic hydroxyl groups and about 5 to about LI-O percent by weight ofan oxyalkylated novolac, until the resulting product is insoluble,infusible and does not soften slightly under mechanical force at atemperature below +00 degrees Fahrenheit, and has substantially nocohesive or bonding strength.

Signed and sealed this 29th day of August 1972 (SEAL) Y EDI ZAI'KD M .lLi'lTC'r-iifil'i, JR. ROBERT GOTTSCHALK Atte sting Officer Commissionerof Patents

